For decades, the Calatrava – the prototype of the classic round wristwatch, including its Officer's style variations with dust covers over the case back – has ranked among the most iconic creations of Patek Philippe. Uniting the key characteristics of this watch family, the new Calatrava Ref. 5227, launched in 2013, now features a display back protected with a separate dust cover. The special twist: the entire hinge is on the inside of the cover, making it invisible even to the connoisseur.